Burglar alarm system



No 24, 1964 R. L. PozNANsKl BURGLAR ALARM SYSTEM Filed sept. 28, 1959 tlriited @rates atent 3,153,850 BURGLAR ALARM SYSTEM Robert L. Poznanski, 918 NW. 19th Ave., Portland, Oreg. Filed Sept. 2S, 1959, Ser. No. 842,917 4 Claims. (Cl. 340-258) This invention pertains to burglar alarms, and relates particularly to a novel burglar alarm system which is constructed to achieve the following objectives:

The burglar alarm system of this invention substantially eliminates the incidence of false alarms. It is constructed to utilize existing telephone lines for connecting the protected area to a police or other guard station. The system is of simplified construction for economical manufacture and compact design, and is characterized by precise and faithful operation with a minimum of maintenance and repair.

The foregoing and other objects and advantages of this invention will appear from the following detailed description, taken in connection with the accompanying drawing, in which:

FIGURE l is a foreshortened blockV diagram illustrating a burglar alarm system embodying the features of this invention; and

FIGURE 2 is a schematic diagram of an electric circuit for the burglar alarm system of this invention.

Referring to FIGURE l, the basic concept of this invention resides in the detection of noise within an area to be protected, for example, within the vault of a bank; the differentiation between normal noises and those created by a burglar, and the utilization of the latter noises to transmit a signal alarm over existing telephone lines 12 to a guard or police station 14.

t In the embodiment illustrated in FIGURE l, an audio t signal microphone pickup 16 is connected to an audio amplifier 18, the output of which functions to activate a t time delay control circuit`20. After a predetermined time delay, which functions to distinguish normal noises from those created by a burglar, the control circuit is rendered operable so that any subsequent noise created by a burglar functions to activate an alarm 22 located at the remote position of a guard or police station.

A preferred embodiment of the invention is illustrated in FIGURE 2. The terminals 24 represent the output of the audio amplifier 18, and the parallel combination of the condenser 26 and relay coil 28 is connected across these terminals. The coil 28 is activated by the noise signal output of the amplifier. Operatively associated with this coil is the normally open relay contact 30. This relay contact is included in a series circuit which extends from one battery terminal 32, such as the negative terminal illustrated, through the normally open switch contact 34 operated by a time clock 36, through the relay contact 30, thence through the normally closed contact 38 of relay coil 40, and the normally closedlcontact 42 of relay coil 44, through the parallel combination of the condenser 46 and relay coil 40, and thence through the normally` closed switch contact 48 of the slow delay relay tube 50, to the opposite battery terminal 52. The normally open contacts and 34 also are included in a series circuit extending from the negative battery terminal 32 through the resistor 54 to the opposite battery terminal 52.

A holding circuit for the relay coil is provided by normally open relay contact 56 which is included in a series circuit extending from the negative battery terminal 32 through the relay contact S6, the relay coil 40 and the Contact 48 of the delay relay tube 5t).

The normally open Contact 58 of relay 40 is included in the electric circuit extending from the negative battery terminal 32 through said contact and thence through the parallel combination of heater filaments of the delay relay nr t i 3,i58,85 Patented Nov. 24, 1964 mice tube 50 and the delay relay tube 60, to the positive battery terminal 52.

The normally open Contact 62 of delay relay tube 60 is included in a series circuit extending from the negative battery terminal 32 through the time clock switch contact 34 and the contact 30 of relay 28, thence through the contact 62 of the delay relay tube 60 and the relay coil-44 it also serves as a remote indicator light to give Visual indication that the alarm has been activated.

In the preferred embodiment illustrated, there is also provided a series electric circuit extending from the negative battery terminal 32 through the normally open contact 76 of relay coil 44, thence through resistor 78 and indicator bulb S0 to the positive battery terminal 52. This indicator bulb may be positioned on the front panel of the vault alarm assembly housing or at any other desired location within the bank, and additional indicator bulbs may be similarly provided and positioned at other desired locations within the bank, to provide visible indication that the burglar alarm system has been activated. When indicator bulb 80 is on, so also is indicator bulb 70.

The relay coil 44 also is provided with another relay contact 82. In the embodiment illustrated, this contact is shown to be normally open and connected across the terminals of the telephone lines 12. These lines extend from the bank to the alarm sounding device 22 located at the remote position of the guard or police station 14. In the embodiment illustrated the alarm device is activated by closing of the normally open contact 82 across the telephone lines, for example, thereby removing a bias voltage which normally maintains the alarm inactive.

In theoperation of the alarm system described hereinbefore let it be assumed that the time clock 36 functions during after-banking hours to maintain its associated switch contact 34 closed. Let it also be assumed, for example, that activation of the delay relay tube 50 functions to open its associated contact 48 after a delay of 60 seconds and that activation of the delay relay tube 60 functions to close its associated contact 62 after a delay of 30 seconds.

Assume now that the microphone 16 located within the bank vault It) picks up a noise signal. This signal is amplified to the desired level by preadjustment of the amplifier 18, and this noise signal thereupon functions to energize the relay coil 28 and momentarily close its associated contact 30. Closure of this contact completes the electric circuit of the relay coil 40, through the contacts 34, 30, 38, 42 and 48, as explained hereinbefore. The relay contact 56 in the holding circuit of the coil 40 is preadjusted to close before the normally closed contact 38 opens, thus maintaining the relay coil 40 energized after the momentarily closed relay contact 30 has opened because of deactivation of the relay coil 28 by cessation of the noise signal.

Activation of the relay coil 40 results in closure of the normally open contact 58 and consequent completion of the electric circuits of the filaments of delay relay tubes 50 and 60. After an initial delay of 30 seconds, the normally open contact 62 of delay relay tube 60 closes, thereby enabling the circuit of relay coil 44 to be completed whenever the normally open contact 30 is closed momentarily in response to a subsequent noise signal produced after the initial 30 second delay and before the termination of an additional 30 seconds, as described more fully hereinafter.

Thus, it is apparent that any noise signals produced before the lapse of the initial 30 seconds will not effect activation of relay coil 44, and consequently these signals will not activate the alarm 22.

Let it now be assumed that a burglar is present Within the vicinity of the vault and that he produces a noise signal after the initial 30 seconds delay. The normally open contact 30 of relay 28 thus is closed momentarily, completing the electric circuit of relay coil 44. Upon activation of this relay, the associated normally open contact 74 is caused to close, thus completing the holding circuit through the reset buttons 64 and 66. The relay coil 44 thus is maintained energized through this holding circuit after the momentarily closed contact 30 of relay 28 has opened upon termination of the noise signal. The reset indicator bulb 70 is energized by completion of the holding circuit, and the other indicator bulb 80 is energized upon closing of the relay contact 76, to give visible indication that the alarm circuit is activated.

Activation of the relay coil 44 also effects closing of the contact 82 across the telephone lines 12, th'us activating the alarm 22 at the guard or police station to give an audible signa-l that a robbery is taking place.

Activation of the relay coil 44 also results in opening of the contact 42 in the initial series circuit of relay coil 40. However, during the 30 second interval following the initial 30 second delay, this relay coil is maintained energized through the holding circuit of contact 56. Upon expiration of this 30 second sensitive period, during which the alarm circuit is sensitive to noise signals, the delay relay tube 50 causes opening of the contact 48, and therefore opening of the holding circuit of relay 40. Deenergization of this relay thereupon causes opening of the con- Y tact 58 in the circuits of the filaments of delay relay tubes 50 and 60, thus returning the associated contacts 48 and 62 to their normal positions indicated in FIGURE 2. Thus, if no noise occurs during this 30 second sensitive interval, the opening of contact 62 returns the alarm automatically to its initial condition, in readiness to repeat the cycle described hereinbefore.

In the event it is desired to inactivate the alarm cir cuit after the alarm has sounded, one of the manual reset buttons 64, 66 may be pressed to open the holding circuit of the relay coil 44.

From the foregoing it will be appreciated that the present invention provides a burglar alarm system which is of simplified construction and capable of precise and faithful operation with a minimum of maintenance and repair. The provision of an initial insensitive period followed by a period of sensitivity to noise signals, serves effectively to differentiate between normal noise signals and those produced by a burglar, thus rendering the sys tem substantially free of false alarm signals.

It will be apparent to those skilled in the art that various changes may be made in the details of construction described hereinbefore without departing from the spirit of this invention and the scope of the appended claims.

I claim:

l. A burglar alarm system comprising an alarm, an

electrical alarm actuator having an electric circuit, first4 and second switches connected in series in the electric circuit of the alarm actuator, an electrical time delay first switch actuator operable by a control circuit actuated by the second switch, a noise responsive actuator operating the second switch, the noise responsive actuator being operable by a first noise signal to actuate the second switch` which activates the control circuit of the time delay actuator whereupon the latter operates the first switch after a predetermined time delay following the first noise signal, a'subsequent noise signal after said predetermined time delay again operating the noise responsive actuator to actuate the second switch whereby to activate the electric circuit of the alarm actuator, a third switch connected in said control circuit of the time delay actuator, and a second electrical time delay actuator operating the third switch, the second time delay actuator also being operable by said control circuit of the first named time delay actuator and being operable after a predetermined time delay longer than the time delay of the first named time delay actuator to operate the third switch and deactivate the first and second time delay actuators.

2. A burglar alarm system comprising an alarm having an electric circuit, an alarm control switch connected in said alarm circuit, an electrical alarm control switch actuator having an electric circuit, a first time delay switch connected in said alarm control switch actuator circuit, a first electrical time delay actuator operating said first time delay switch and having an electric circuit, a first time delay actuator control switch connected in said first time delay actua-tor circuit for controlling operation of said actuator', an electrical actuator operating said first time delay actuator control switch and having an electrical circuit, a second time delay switch connected in said first time delay actuator control switch actuator circuit, a second electrical time delay actuator operating said second time delay switch and having an electric circuit controlled by said first time delay actuator control switch, a noise signal-actuated switchcontrolling said circuits of I the -alarm control switch actuator and the actuator for said first and second time delay actuator control switch, a noise signal responsive actuator operating the noise signal-actuated switch, and a holding circuit operable by said first time delay actuator control switch actuator to bypass the noise signal-actuated switch, the holding circuit including said second time delay switch, the time delay for actuation of said second time delay switch being greater than the time delay for actuation of said first time delay switch.

3. The alarm system of kclaim 2 including a holding circuit operable by said electrical alarm control switch actuator to bypass said rst time delay switch and said noise signal-actuated switch.

4. The alarm system of claim 2 including a control switch connected in said first time delay actuator control switch actuator circuit and operable by the alarm control switch actuator to open said circuit.

References Cited in the file of this patent UNITED STATES PATENTS 1,643,759 Adams Sept. 27, l1927 2,007,371 Hopkins July 9, 1935 I. 2,008,408 Thompson July 16, 1935 2,235,928 Hardinge Mar. 25, 1941 2,578,347 Gagnaire Dec. ll, 1951 2,701,874 Mears Feb. 8, 1955 

1. A BURGLAR ALARM SYSTEM COMPRISING AN ALARM, AN ELECTRICAL ALARM ACTUATOR HAVING AN ELECTRIC CIRCUIT, FIRST AND SECOND SWITCHES CONNECTED IN SERIES IN THE ELECTRIC CIRCUIT OF THE ALARM ACTUATOR, AN ELECTRICAL TIME DELAY FIRST SWITCH ACTUATOR OPERABLE BY A CONTROL CIRCUIT ACTUATED BY THE SECOND SWITCH, A NOISE RESPONSIVE ACTUATOR OPERATING THE SECOND SWITCH, THE NOISE RESPONSIVE ACTUATOR BEING OPERABLE BY A FIRST NOISE SIGNAL TO ACTUATE THE SECOND SWITCH WHICH ACTIVATES THE CONTROL CIRCUIT OF THE TIME DELAY ACTUATOR WHEREUPON THE LATTER OPERATES THE FIRST SWITCH AFTER PREDETERMINED TIME DELAY FOLLOWING THE FIRST NOISE SIGNAL, A SUBSEQUENT NOISE SIGNAL AFTER SAID PREDETERMINED TIME DELAY AGAIN OPERATING THE NOISE RESPONSIVE ACTUATOR TO ACTUATE THE SECOND SWITCH WHEREBY TO ACTIVATE THE ELECTRIC CIRCUIT OF THE ALARM ACTUATOR, A THIRD SWITCH CONNECTED IN SAID CONTROL CIRCUIT OF THE TIME DELAY ACTUATOR, AND A SECOND ELECTRICAL TIME DELAY ACTUATOR OPERATING THE THIRD SWITCH, THE SECOND TIME DELAY ACTUATOR ALSO BEING OPERABLE BY SAID CONTROL CIRCUIT OF THE FIRST NAMED TIME DELAY ACTUATOR AND BEING OPERABLE AFTER A PREDETERMINED TIME DELAY LONGER THAN THE TIME DELAY OF THE FIRST NAMED TIME DELAY ACTUATOR TO OPERATE THE THIRD SWITCH AND DEACTIVATE THE FIRST AND SECOND TIME DELAY ACTUATORS. 